A filter which prevents a high frequency noise current from propagating to a cable via a connector is disclosed in Japanese Patent Laying-Open No. 2009-105575. In the filter disclosed in Japanese Patent Laying-Open No. 2009-105575, a region which exhibits high impedance is formed at a portion around a connector of the printed circuit board. The region which exhibits high impedance has an electromagnetic band gap structure having a band gap which prevents propagation of electromagnetic waves at a prescribed frequency band. A surface structure which exhibits high impedance at a plurality of frequency bands is disclosed in U.S. Pat. No. 6,483,481.
The region which exhibits high impedance includes a plurality of conductor pieces disposed at a first conductor layer periodically, a ground conductor film disposed at a second conductor layer, and a conductor pillar which connects the plurality of conductor pieces to the ground conductor film.